HP 8340A, Руководство по обслуживанию

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Model 8340A - Service
The 100 MHz OUT signal at Jl and J2 and the 400 MHz OUT signal are
set to the correct power level by resistive pads (R30, R31, and
R32; R33, R34, and R35; and R67, R68, and R69). The attenuation of
these pads is selected to give the required power. For a given
level of attenuation, the required resistor values are given in
Table 8B-3.
·
Table 8B-3. Attenuation and Resistor Values for 100 MHz OUT and 400 MHz OUT
RESISTORS {OHMS)
ATTENUATION R30
R31 R32
( d B)
R33 R34 R35
R67 R68
R69
3 261
17.8
261
4
215
23.7 215
5 178 31. 6 178
6
147
38.3
147
7 133
46.4 133
8 121 51.1
121
9 110 61.9
110
Quadrupler C and 400 MHz Amplifier D
The 400 MHz OUT signal level should be between -9 and -11 dBm. If
the signal level is outside these limits, then check also the
harmonic levels (see below). If they are out of spec, then make
the adjustment of C2 and C3 and then recheck the signal level. If
the harmonic levels are correct and the signal level is still low
or if the 400 MHz signal is missing, and if the 100 MHz OUT
signals are correct, then troubleshoot the signal path that
includes the 100 MHz Buffer Amplifier Q7 (Block B), the Quadrupler
transistors Q3 and Q4, and the 400 MHz Amplifier Q2 and Ql. The
typical bias voltage levels for Ql-4 are given in Table 8B-4. To
adjust the 400 MHz OUT power level to the required level, then
change R67, R68, and R69, referring to Table 8B-3 for values.
8-113
Scans by HB9HCA and HB9FSX